A. B is the two points on the line EF. It is known that EA: ab: BF = 1:2:3, m and N are the midpoint of EA and BF respectively, and Mn = 8cm

A. B is the two points on the line EF. It is known that EA: ab: BF = 1:2:3, m and N are the midpoint of EA and BF respectively, and Mn = 8cm

∵ EA: ab: BF = 1:2:3, let EA = x, ab = 2x, BF = 3x, and m and n be the midpoint of EA and BF respectively, ∵ Ma = 12ea, Nb = 12bf, ∵ Mn = ma + AB + BN = 12x + 2x + 32x = 4x, ∵ Mn = 8cm, ∵ 4x = 8, ∵ x = 2, ∵ EF = EA + AB + BF = 6x = 12, ∵ EF = 12cm